EtAl/Light-Promoted Radical-Polar Crossover Reactions of α-Alkoxyacyl Tellurides.

Here, we report new radical-polar crossover reactions of α-alkoxy carbon radicals for constructing highly oxygenated molecules with contiguous stereocenters. The method employs a 370 nm UV light-emitting diode (LED) for the photoexcitation of α-alkoxyacyl telluride, and EtAl as the radical initiator and terminator. First, EtAl and UV LED promoted radical coupling between the α-alkoxyacyl telluride and cyclopentenone via C-Te bond homolysis, CO expulsion, and C-C bond formation.

Conversion of Phorbol into Des-D-Ring Tricycle and Crotonianoid B via Peroxidation Reaction.

Phorbol () has a tetracyclic ABCD-ring and is readily isolable from a natural source. We previously synthesized and 16 structurally related natural products using common ABC-ring intermediate . Here we report a new synthetic route to using as a starting material.

Total Syntheses of Phorbol and 11 Tigliane Diterpenoids and Their Evaluation as HIV Latency-Reversing Agents.

Tigliane diterpenoids possess exceptionally complex structures comprising common 5/7/6/3-membered ABCD-rings and disparate oxygen functionalities. While tiglianes display a wide range of biological activities, compounds with HIV latency-reversing activity can eliminate viral reservoirs, thereby serving as promising leads for new anti-HIV agents. Herein, we report collective total syntheses of phorbol () and 11 tiglianes - with various acylation patterns and oxidation states, and their evaluation as HIV latency-reversing agents.

Total Synthesis of Taxol Enabled by Intermolecular Radical Coupling and Pd-Catalyzed Cyclization.

Taxol () is a clinically used antineoplastic diterpenoid. The tetracyclic ring system comprises a 6/8/6-membered carbocycle (ABC-ring) and a fused oxetane ring (D-ring) embedded with a bridgehead double bond and decorated with multiple oxygen functionalities. Here, we report a convergent total synthesis of this exceedingly complex natural product.

Total Synthesis of Taxol Enabled by Inter- and Intramolecular Radical Coupling Reactions.

Taxol is a clinically used drug for the treatment of various types of cancers. Its 6/8/6/4-membered ring (ABCD-ring) system is substituted by eight oxygen functional groups and flanked by four acyl groups, including a β-amino acid side chain. Here we report a 34-step total synthesis of this unusually oxygenated and intricately fused structure.